It could be the cutbacks to the city’s transportation system, or a general decline in urban civility. Perhaps people are just in a collective bad mood.

What else could explain why New Yorkers — notoriously hardened to the slings and arrows of everyday life here — are spitting on bus drivers?

Of all the assaults that prompted a bus operator to take paid leave in 2009, a third of them, 51 in total, “involved a spat upon,” according to statistics the Metropolitan Transportation Authority released on Monday. No weapon was involved in these episodes. “Strictly spitting,” said Charles Seaton, a New York City Transit spokesman.

And the encounters, while distressing, appeared to take a surprisingly severe toll: the 51 drivers who went on paid leave after a spitting incident took, on average, 64 days off work — the equivalent of three months with pay. One driver, who was not identified by the authority, spent 191 days on paid leave.

Transit officials, facing a budget shortfall of $400 million, called the numbers troubling. “We have to see what we’re going to do with that,” said Joseph Smith, who oversees bus operations for New York City Transit.

Spitting falls under the category of assault in the drivers’ contract with the authority. And officials at Transport Workers Union Local 100, which represents city bus operators, said the extended absences were justified.

“Being spat upon — having a passenger spit in your face, spit in your mouth, spit in your eye — is a physically and psychologically traumatic experience,” said John Samuelsen, the union’s president. “If transit workers are assaulted, they are going to take off whatever amount of time they are going to take off to recuperate.”

Sensitivities have been heightened since 2008, when Edwin Thomas, a bus driver in Brooklyn, was stabbed to death by a passenger after an argument over the fare. In response, the authority offered classes to drivers on defusing tense situations. Plastic partitions for drivers have been tested, but a design has not been set.

Yet spitting assaults have grown. More than 80 drivers reported being spat upon in the last year, the authority said.

Enforcement may be an issue. Almost no arrests have been reported for spitting on a driver, said Mr. Smith, who noted that a police officer “must witness the spat upon to give a summons.”

London and other cities have found a novel solution: collecting the DNA of the offending spitters.

(snip)

Raul Morales, 52, has been driving city buses for five years, but his first encounter with spit came early.

“A guy wanted to get on the bus; I told him the fare; he didn’t want to pay it,” Mr. Morales said. “So, he spat at me.”

The spittle landed on his shirt and glasses. He stopped at a nearby McDonald’s to clean himself off, then finished his shift. “I just kept on going.” (An ice slushie was once thrown at him for the same reason.)

Having someone spit on you is disgusting and maybe even enraging but it isn't a serious health threat and it shouldn't be a serious psychological issue.